Preparation And Application In CH₄-CO₂ Reforming Of Carbon Materials From Direct Coal Liquefaction Residue

Direct coal liquefaction residue (CLR) shares about 20 wt.%～30 wt.% of the raw coal used in the direct coal liquefaction process. It is necessary to effectively utilize CLR for the benefits of the process and developing clean and efficient coal technologies. What’s more, plenty of CH4 and CO2 is emitted in the process of coal carbonization and gasification, these exhaust gas has a low chemical utilization rate. Based on the above, this paper put forward that various CLR can be used to prepare carbon materials, the CLR based carbons can be used as catalysts for synthesis gas production by catalytic methane reforming carbon dioxide.Various CLR based carbons were prepared by KOH activation and the preparation was carried out in a tubular furnace. The crude materials obtained after activation was treated by grinding, washing, filtering and drying. The CLR based carbons were characterized by thermo gravimetric (TG), scanning electron microscope (SEM), specific surface area measurement (BET), X-ray diffraction (XRD), transform infrared spectrometer (FT-IR) and fixed-bed.Results of carbon material preparation show that:the CLR based carbons have large specific surface area, when the mass ratio of KOH/CLR is 3, carbonization temperature is 450 ℃, activation temperature is 850℃, the yield of carbon material is 43.1%, the specific surface area is 1631 m2/g; CLR, after pre-oxidation by KNO3, also can be used to prepare carbon materials, which have higher specific surface, pore volume and high degree of graphitization comparing with no KNO3 oxidation; With the weight ratio of KOH/CLR increasing from 1 to 3, the CLR based carbons tend to have larger specific surface, lower yield and lower degree of graphitization; carbon materials obtained by acid pickling have less mineral comparing with those carbon materials obtained by washing used water; the CLR based carbons have similar functional groups, mainly include ether, carboxyl and phenolic-hydroxyl groups, they have rough surface with a large number of pores distributed in the above.The experiment of CH4-CO2 reforming reaction catalyzed by carbon material was carried out in a fixed bed reactor at atmospheric pressure, results show that:the CLR based carbon material have good catalytic activity for CH4 reforming CO2; CLR, after pre-oxidation by KNO3, can be prepared into carbon materials which have higher catalytic activity; With the weight ratio of KOH/CLR increasing from 1 to 3, the catalytic ability of carbon materials is also gradually improve; Carbon materials obtained by washing used water is better than the materials obtained by acid pickling, which is reflected in the long time stability; the conversion rate of CH4 and CO2 decreased first, then increased gradually up to the maximum, then decreased after a long time; The mass of carbon material decreased a lot after reaction.